[SCSI] fcoe: remove a stray unlock

We moved the locking in dd060e74 "[SCSI] fcoe: remove frame dropping
code from fcoe_percpu_clean" but this unlock was missed.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>